Drill bit



Nov. 26, 1935. R. R. SANDERSON ets-Sheet 1 Filed July 30, 1932 2 SheINVENTOR 0: R. Sanderson Y /Mf A'ITORNE Nov. 26, 1935. R. R. SANDERSONDRILL BIT Filed July 30, 1932 2 Sheets-Sheet 2 l l l l l I i I I I l I Ill 7, INVENTOR B BY R- Sanderson Patented Nov. 26, 1935 UNITED STATESPATENT OFFICE 7 Claims.

This invention relates to assembled drill bits comprising a blade andremovable tip for usein churn and percussion drilling and more particu,'larly to means for securing the drill bit tip to the drill bit blade,and is an improvement of the drill bit assembly shown and described inmy co-pending application Serial No. 614,866 that was filed June 2,1932.

Drill bits conventionally used in churn and percussion drilling arecommonly of single piece construction and are of great weight. In thepast it has been the practice when using a bit of this type to disengagethe entire bit from the drill stem when the cutting tip of the bit dullsor when the character of the particular formation in which the bit isbeing used changes so that a difierent form of cutting edge of the bitis advisable. The labor and time required for removing and replacingsuch bits by bits of proper character for use in the particularformation being worked in, and the expense and delay incident toresharpening drill bits in the field, discouraged the changing of suchdrill bits before it was absolutely necessary. The equipment forproperly dressing and tempering drill bits in the field is so limitedthat the best tempering and dressing is seldom achieved.

Removable drill bit tips heretofore proposed for use in churn drillinghave not been satisface tory for commercial use because of the inherentweakness of the union between the bit tip and the blade, the tendency ofthe union between the bit tip and the bladeto loosen in service and forother reasons. So far as known, no commercially satisfactory removabledrill bit tip for churn drilling has been produced heretofore, althoughthe need for such removable drill bit tips has been fully recognized inthe industry.

Many distinct advantages accrue from the use of inexpensive,properlyhardened and properly shaped drill bit tips in the industry.Removable drill bit tips may be made from the best character ofmaterials for the service expected ofthem and the forming, sharpeningand tempering of the bit tip may be carefully controlled by factoryequipment, so that greatly superiorcutting edges for the tools areproduced, the drill bit tips wear longer in service and the ease withwhich such drill bit tips may be changed induces the driller to makedesirable changesin the drill bit tip for different character of rockformation which otherwise would not be made,

In accordance with the present invention, a single drill bit bladeforming a piece of perma-' nent equipment may be carried to the site ofthe drilling operation along with a plurality of interchangeable drillbit tips of various and desirable design of cutting edge adapted to theparticular rock'structure characteristic of that region. This greatlydecreases the expense and labor involved 5 in carrying two or more ofthe heavy, cumbersome and unwieldly drill bits to the site of thedrilling, which has been the practice in the past. One of the objects ofthe present invention is to provide a drill bit assembly which permits1Ql quickand easy interchange of drill bit tips upon the end of a drillbit blade, so that a plurality of such drill bit tips may beconsecutively and inter-v changeably used in replacing a bit tip madedull or worn in the drilling operation or for drilling 15;

different characters of rock or ground formation, the cutting'edge ofthe drill bit tip being unbroken by wrench-receiving apertures forassembling and disassembling the bit tip.

-A further object of the invention is to provide 20 a drill bit tip andblade assembly embodying means for securing the drill bit tips to thedrill bit blade, which securing means is confined entirely within theassembled. drilling tool and wherein no apertures extend into thecutting face 25 of the tool. I i V A further object is to provide adrill bit tip in combination with means for rigidly securing the bittips to a bit blade in such a manner that the blade and'tip cannot bereadily separated 30 from or be deformed while in a drill holeirrespective of the angular torque to which the junc tion of the drillbit tip and drill blade is subjected.

Another object is to provide a drill bit blade 35 and tip assembly inwhich the drill bit tip has an unbroken cutting edge and may be quicklyand easily replaced so that the proper shape and design of drill bittips to provide the most rapid cutting rate .and a maximum length oflife for 40 each character of rock may be secured tov the end of thedrill bit blade without objectionablelabor. V

With the above and other objects in view, which will be readily apparentfrom the follow- 45 ing detailed description,- the present inventionconsists in certain constructions andcombinations of parts which will bereadily understood by those skilled in the art to which the inventionappertains. r Y

In the accompanying drawings, which illustrate suitable embodiments ofthe presentinvention, Fig. 1 is a side elevational view partly insection of a preferred means for securing a drill bit tip to a drill bitblade; .7

Fig. 2 is an end elevational view of the assembled bit shown in Fig. 1;

Fig. 3 is a transverse sectional view taken along line 3-3 of Fig. 1;

Fig. 4 is a side elevational view of a modified form of means forsecuring the drill bit tip to the drill bit blade;

Fig. 5 is a transverse sectional view taken along line 5-5 of Fig. 4;

Fig. 6 is a side elevational view shown partially in section of a secondmodification of means for securing a drill bit tip to a drill bit blade;

Fig. 7 is a side elevational view shown partially in section of a thirdmodification of the preferred form of securing means for securing adrill bit tip to a drill bit blade.

The drill bit assembly shown in Figs. 1, 2 and 3 comprises a drill bitblade I to which a drill bit tip 2 is rigidly secured by means of theanchor stud 3 that is preferably disposed centrally and longitudinallyof the drill bit blade. A plurality of keys, dowels or other suitablemembers 4 are positioned in apertures formed in the drill bit blade andthe drill bit tip at their junction, and serve to effectively preventrotation between these members.

In the preferred form of drill bit assembly the anchor stud 3 ispositioned within an aperture 5 disposed centrally and longitudinally ofthe drill bit blade and an internally threaded aperture 6 formed in thedrill bit tip. The aperture 5 opens upwardly into a transverselydisposed wrenchreceiving aperture II that is positioned somewhat awayfrom the end of the drill bit blade. The stud-receiving portion of theaperture 5 is suitably threaded for receiving the anchor stud 3. Thethreaded portions 9 of the aperture 6 formed in the drill bit tip andthe threaded portion 8 of the aperture 5 formed in the drill bit bladeare preferably of opposite direction.

The anchor stud 3 is preferably provided with suitable wrench engagingmeans, such as-a plurality of internal splines III, at its upperextremity I. Other means may be provided for the rotation of the stud 3,such as external wrench squares or other suitable means. The aperture IIis cut transversely of the drill bit blade in such a manner as to permitfree access to the wrench-receiving end of the stud.

As in all constructions of the removable drill bit tip, the impact faceI2 of the drill bit blade and the impact face I3 of the drill bit tipare each designed to be substantially perpendicular to the longitudinalaxis of the drill bit blade.

Dowel apertures I4 and I5 formed in both the drill bit blade and thedrill bit tip are designed to index accurately with each other for theaccommodation of the dowels or keys 4.

In assembling the preferred form of drill bit tip and blade, suitabledowels 4 are inserted into the apertures I5 in the drill bit tip and theanchor stud 3 rotated by means of a splined wrench socket II) to drawthe impact faces I2 and I3 rigidly together.

In order to remove a' worn drill bit tip from the drill bit blade uponwhich it is mounted the above operations need only be reversed.

The structure shown in Figs. 4 and Fig. 5 comprises a drill bit blade Iand a drill bit tip 2 secured together by means of the bolt I8 that 'issecured within the internally threaded aperture I9 formed within thedrill bit tip I. The upper end of the bolt I8 has a rack nut 20 threadedthereto. The rack nut 20 carries a plurality of blade I for theaccommodation of the rack nut 2! The shoulder 24 of the rack nut 25B isdesigned to rest in compressing relation against the shoulder 25surrounding the bolt-receiving aperture formed in the drill bit blade tolock the bit tip in place and to substantially exclude water from accessto the threaded portions of the bolt I-8. Suitable dowels 25 or othermeans serve to prevent rotation of the drill bit tip 2 relative to thedrill bit blade I.

The construction shown in Figs. 4. and 5 provides a very simple andrapid means of assembling and disassembling a drill bit tip upon the endof a drill bit blade. This construction has the further advantage thatit also substantially seals the threaded portion of the assembly boltfrom water that tends to corrode the parts.

The construction shown in Fig. 6 comprises a drill bit blade I to theend of which the drill bit tip 2 is secured by means of the headed bolt27 having a threaded lower end 28 that engages the internally threadedaperture 29 formed in the drill bit tip and extending along the aperture38 formed centrally and axially of the drill bit blade I. The bolt headhas a suitable splined wrench socket formed therein for turning thebolt. The assembly of the bit tip for this construction will be obvious.The pin of the drill stem (not shown) is then assembled in place. Thereverse operation is necessary for the removal of the bit tip.

This form of construction has some advantages over previously describedconstructions. The assembly bolt may be placed under sufiicient tensionto prevent dislodgment of the bit tip even under severe impacts thatsomewhat compress the body of the bit blade. The bolt may be made of ahigh tensile steel that will meet the needs of this service.

The necessity of breaking the joint with the drill stem when a new bittip is installed has the advantage of insuring that this joint is tightbefore the tool is replaced in the hole. Many times tools are lost in ahole because of failure to tighten this joint before the tool isreplaced in the hole.

In this assembly the only joint that might permit the ingress of waterto the mechanical parts of the assembly is between the impact faces and,since these are ground faces, they are tight and seal the mechanicalparts.

The assembly shown in Fig. 7 comprises a drill bit blade I and a drillbit tip 2 secured together by means of the elongated bolt 43 termihatingat its lower end in the right-left threaded portions 44 and 45 and atits upper extremity in the wrench square portion 45. The threadedportion 44 at the lower extremity of the bolt 43 is designed to threadinto the internally threaded aperture 41 formed in the drill bit tip 2.The threaded portion 45 of therelongated bolt 43 is preferably of twicethe length of the threaded portion 44, since as the drill bit tips arereplace- 'able, it is much more important to protect the threaded areaof the bolt 43 which is positioned face of the drill bit tip is withinthe drill bit blade' 2 than the portion securing the bit tips inplace.flSuitable dowels 48 are seated within dowel apertures to preventrotation of the bit tip, The assembly of this structure is the same asthe assembly of the structure shown in Fig. 6, and many of theadvantages are common. The use of the right-left threaded assembly boltalso has the self-tightening features described in my copendingapplication previously referred to.

It will be noted that in each of the embodiments'of the invention shownherein the cutting unbroken, and that there are no projections on thesides of the bit assembly that retardthe free fall of the bit assemblyin service. The substantially sealed joint between the impact facesexcludes water and prevents corrosion of the assembly parts of the bit.

It is to be understood that the particular embodiments of the presentinvention shown and described are presented for purposes of illustrationand explanation, and that various modifications, including the form ofwrench socket or wrench connecting means or the type of dowel or keyused for preventing rotation of the drill bit tip, may be made withoutdeparting from the invention as defined in the appended claims.

What I claim is:

1. A drill bit, comprising a bit blade having a bolt-receiving socketand a wrench aperture ex-, tending transversely of an intermediateportion thereof and connected with the bolt-receiving socket, a bit tiphaving a cutting face and a bolt-receiving socket arranged in registeredrelation with the corresponding socket of said bit blade and closed atthe end adjacent the cutting face, a bolt for securing said partstogether, an impact transmitting face formed on said blade and acorresponding impact-receiving face formed on said tip and arrangednormal to the longitudinal axis of said bit blade, and interfittingmeans on said blade and tip laterally offset from said sockets forpreventing relative rotary movement of said bit tip relative to said bitblade. 4

2. A drill bit tip and drill bit blade asembly for churn and percussiondrilling, comprising a drill bit tip having an internally threadedstud-receiving socket with closed bottom formed therein and opening thruan impact face formed on said bit tip, a bit blade having an impact faceregistering with the impact face of the bit tip and when assembled saidbit blade and bit tip having a 'smooth and continuous external surfacealong their junction and a bolt-receiving aperture formed longitudinallyof said bit blade and opening at one end into an internally threadedstud-receiving socket formed in said bit blade and opening at its otherend into a wrench aperture formed transversely of said bit blade, an

anchor stud having externally threaded end portions of oppositelydirected threads and serving to secure the impact faces of said bitblade and said bit tip together, and wrench engaging means forming apart of said anchor stud and accessible in said wrench aperture fromoutside the drill bit after assembly of the bit tip and the bit bladeJ3. A drill bit for churn and percussion drilling, comprising a bit bladehaving an impact face forming the lower end of said bit blade and beingsubstantially normal to the longitudinal axis of said bit blade, a bittip having a continuous cutting edge and having an impact face of conaspreviously explained.

tour and areasubstantially conforming with the contour and arearespectively of the impact face of said bit blade and arranged to formuniformly dowel sockets on opposite "l'novement between close contacttherewith, separate means that is partially housed within both said bitblade and 5 saidbit tip and passing thru the contact plane of the impactface of said bit blade with the impact face of said bit tip forpreventing relative rotary 7 said bit tip and said bit blade, a bolt forsecuring said bit tip to said bit blade, and wrench engaging means forrotating said bolt and that is positioned within anaperture formedwithin said bit blade in such a manner as to be operable from outsidethe drill bit after assembly of the bit tipand the bit blade.

4. A blade and tip assembly for churn and percussion drills comprising ablade having a central aperture, a wrench receiving opening incommunication with said aperture, a tip having a cutting edge at oneside and a central threaded 20 bolt socket at the other side, saidsocket being closed adjacent said edge, said blade and tip having impacttransmitting and receiving surfaces in engagement with each other, meansoutwardly of said central aperture for locking said tip and bladeagainst relative rotation, and bolt means disposed within said centralaperture and threaded into said socket, said bolt means having portionsinterfitting with said blade whereby to hold said blade and tip againstrelative longitudinal movement, said bolt means being accessible throughsaid wrench receiving opening, said opening being disposed through saidblade transversely of said central aperture.

5. A drill bit for churn or percussion drilling comprising a bit bladehaving an impact transmitting lower end face substantially normal to itslongitudinal axis, a longitudinal bore opening to said lower end faceand dowel sockets opening only to the lower end face inwardly of itsmar- 40 gin and laterally of said bore, a bit tip adapted to form acontinuation of the blade and having an upper impact receiving faceconforming to the lower end face of the blade and adapted to seatagainst said end face of the blade, said bit 45 tip having athreadedsocket adapted to register with the bore of the blade and dowelsockets adapted to register withthe sockets of the blade, the sockets ofthe bit opening only to the upper face thereof, dowels adapted to extendacross 50 the contacting faces of the blade and drill bit with theirupper ends in the sockets of the blade and their lower ends in thesockets of the drill bit, and means for clamping the drill bit againstthe lower end of the blade comprising a bolt in the bore of the bladewhich has a threaded lower end adapted to screw into the threaded socketof the bit tip.

6. A drill bit for churn or percussion drilling comprising a bit bladehaving a flat impact imparting lower end face normal to the axis of theblade, an axial bore opening at its lower end to said face and dowelsockets on opposite sides of the axial bore and opening only to thelower end face, a bit tip of the upper portion of which is of the samesize and shape as the lower end of the blade, said bit tip having a fiatimpact receiving face adapted to seat against the lower end face of theblade, a central threaded socket opening only to the upper face thereofand adapted 70 to register with the axial bore of the blade and sides ofthe socket opening only to the upper face of the bit tip, said bit tiphaving bottom faces tapering to a cutting edge normal to the axis anddirectly beneath 7 5 tact between the abutting faces of the blade andbit tip, and means for clamping the bit tip to the blade comprising abolt threaded in the central socket of the bit tip and extending throughthe axial bore of the blade.

7. A drill bit for churn or percussion drilling comprising a bit bladehaving an impact transmitting lower end face substantially normal to itslongitudinal axis and a longitudinal bore opening to said lower endface, a bit tip adapted to form a continuation of the blade and havingan upper impact receiving face adapted to seat against the lower endface of the blade, said bit tip having a threaded socket opening only toits upper face and adapted to registerwith the bore of the blade, keymembers disposed between the boreand margins 101 the contacting facesfor holding the bit tip against turning movements with respect to theblade, and permitting axial movement of the tip toward or away from theblade, and a ,bolt in the bore :of the blade having a threaded lower endadapted to screw into the socket of the bit tip, said bolt having wrenchreceiving means at its upper end and with end thrust receiving partscoacting with the body of the blade whereby the bolt may be actuated toexert a thrust on the bit tip in a direction to clamp the bit-tip to theblade-or in the opposite direction to separate the bit tip from theblade.

RAY R. SANDERSON.

